misc: do not ignore empty block rows when evaluating live value for js (#81094)

tests/form_pages/test_block.py

@@ -2100,6 +2100,61 @@ def test_block_with_block_item_field_condition_and_prefill(pub):
     assert resp.form['f1$element0$f234'].value == 'Bar'
 
 
+def test_block_with_block_empty_row_and_condition(pub):
+    BlockDef.wipe()
+    block = BlockDef()
+    block.name = 'foobar'
+    block.fields = [
+        fields.StringField(id='123', required=True, label='One', varname='one'),
+        fields.StringField(
+            id='234',
+            required=True,
+            label='Two',
+            condition={'type': 'django', 'value': 'block_var_one'},
+        ),
+    ]
+    block.store()
+
+    FormDef.wipe()
+    formdef = FormDef()
+    formdef.name = 'form title'
+    formdef.fields = [
+        fields.BlockField(id='1', label='test', block_slug='foobar', max_items=3),
+    ]
+    formdef.store()
+    formdef.data_class().wipe()
+
+    app = get_app(pub)
+    resp = app.get(formdef.get_url())
+    resp.form['f1$element0$f123'] = 'foo'
+    resp = resp.form.submit('f1$add_element')
+    resp.form['f1$element1$f123'] = 'bar'
+    resp = resp.form.submit('f1$add_element')
+    resp.form['f1$element1$f123'] = ''
+    resp.form['f1$element2$f123'] = 'baz'
+
+    live_resp = app.post(
+        formdef.get_url() + 'live',
+        params=resp.form.submit_fields(),
+    )
+    assert live_resp.json['result']['1-234-0']['visible'] is True
+    assert live_resp.json['result']['1-234-1']['visible'] is False
+    assert live_resp.json['result']['1-234-2']['visible'] is True
+
+    resp.form['f1$element0$f234'] = 'foo2'
+    resp.form['f1$element2$f234'] = 'baz2'
+    resp = resp.form.submit('submit')  # validation
+    resp = resp.form.submit('submit')  # -> end page
+    formdata = formdef.data_class().select()[0]
+    assert formdata.data == {
+        '1': {
+            'data': [{'123': 'foo', '234': 'foo2'}, {'123': 'baz', '234': 'baz2'}],
+            'schema': {'123': 'string', '234': 'string'},
+        },
+        '1_display': 'foobar, foobar',
+    }
+
+
 def test_formdata_page_with_block_bad_value(pub):
     BlockDef.wipe()
     user = create_user(pub)

wcs/blocks.py

@@ -417,7 +417,7 @@ class BlockSubWidget(CompositeWidget):
                 all_lists = False
             if widget_value.get(widget.field.id) not in empty_values:
                 empty = False
-        if empty and not all_lists:
+        if empty and not all_lists and not get_publisher().keep_all_block_rows_mode:
             value = None
         self.value = value
 

wcs/forms/root.py

@@ -1686,7 +1686,10 @@ class FormPage(Directory, TempfileDirectoryMixin, FormTemplateMixin):
         formdata = self.get_transient_formdata()
         get_publisher().substitutions.feed(formdata)
         displayed_fields = []
-        with get_publisher().substitutions.temporary_feed(formdata, force_mode='lazy'):
+        with (
+            get_publisher().substitutions.temporary_feed(formdata, force_mode='lazy'),
+            get_publisher().keep_all_block_rows(),
+        ):
             form = self.create_form(page=page, displayed_fields=displayed_fields, transient_formdata=formdata)
         try:
             formdata.data.update(self.formdef.get_data(form, raise_on_error=True))

wcs/publisher.py

@@ -635,6 +635,19 @@ class WcsPublisher(QommonPublisher):
         finally:
             self.inspect_recurse_skip_prefixes = None
 
+    # when parsing block widgets we usually want to skip empty rows, however
+    # when evaluating live conditions we must keep all lines to get row indices
+    # matching what's in the DOM.
+    keep_all_block_rows_mode = False
+
+    @contextmanager
+    def keep_all_block_rows(self):
+        self.keep_all_block_rows_mode = True
+        try:
+            yield True
+        finally:
+            self.keep_all_block_rows_mode = False
+
     def clean_deleted_users(self, **kwargs):
         for user_id in self.user_class.get_to_delete_ids():
             self.user_class.remove_object(user_id)